In general, a medical radiography device, which radiates X-rays to a human body and detects a difference in energy intensity distribution of the X-rays, falls into an analog type and a digital type.
The analog type, which uses an intensifying screen (fluorescent plate) and a silver halide film, makes a latent image on the silver halide film using light from the intensifying screen and then obtains a visual image by chemically processing the silver halide film. In the process of developing, costs are continuously generated, the film needs to be carefully managed, and waste water deteriorates the environment of a hospital.
On the other hand, the digital type, which uses a 2D sensor as a detector responding to X-rays, obtains a minute electrical signal generated by the sensor through a 2D matrix, converts an amplified signal into a digital value using an amplifying circuit that amplifies the minute signal, and an analog/digital converter makes an image data from the digital value and then displays an image through a monitor or a printout after performing appropriate imaging processing.
Digital radiography devices are used in dentistry to diagnose teeth and check whether prostheses have been correctly installed. Related thereto, a “Portable digital X-ray system” has been disclosed in Korean Patent Application Publication No. 10-2002-0008810. The system in the cited publication can be mounted with a vehicle, unlike a fixed type of the related art, but cannot be easily carried by a user.
Korean Patent Application Publication No. 10-2005-0090667 has proposed an apparatus of which the material and the mechanical configuration have been manufactured to be carried, but it does not consider the radiation time or the exposure dose of X-rays, so a patient is exposed to X-rays for too much time and it is inconvenient to use the apparatus due to heavy weight.
Korean Patent Application Publication No. 10-2008-0005000 has proposed a configuration that connects one or more diode in parallel to improve tube voltage and tube current ripples by improving a switching frequency and apply load corresponding to momentary load to a side of a diode where voltage is firstly applied in a multiplier circuit including a plurality of condenser and diodes connected to each other, in order to be applied to an X-ray generator of 100 kHz as a way of reducing an exposure dose.
However, arranging diodes in parallel to protect them from overcurrent is not actually needed because the current range used for X-rays is low and narrow. Further, a temporary peak voltage is generated at the output port of a high-voltage transformer and accordingly X-rays cannot be accurately controlled, so obtained images are dim or milky white and the lifespan of an apparatus may be reduced. Accordingly, it is required to maintain a predetermined voltage without overvoltage.
Further, increasing a switching voltage causes a problem with insulation, but the configurations described above do not consider this insulation problem, so complete insulation is strongly required.
Further, dental radiograph devices of the related art cannot be simply operated for patients, so it is required to further reduce the size and weight and ergonomically design the devices to conveniently use them for a longer period of time for patients.
Further, it has been reported that the more dental X-ray treatments a patient receives, the larger the danger of thyroid gland-related disease becomes, maximally by five times (by Dr. Anjum Memon, Brighton-sussex medical college, U.K), but X-ray generators using high frequencies use a switching frequency of 40 kHz or less in our country, so ripples are large and a rising time and a falling time are long, which increases an X-ray exposure dose, and accordingly, it is an urgent need to solve this problem. Further, since electronic parts are also reduced in lifespan when they are exposed to X-rays for a long period of time, it is difficult to use expensive equipment for a long period of time.